> > 4) "Later - Version 2.0" - You are not happy with the response,
> > but are prepared to defer consideration until XML Schema Language
> > Version 2.0 is drafted. It is anticipated that Version 2.0 would
> > not be completed until late 2001 or early 2002. Version 2.0 may
> > include major revisions, e.g., multiple inheritance, etc.
> > You request that your comments be reconsidered when drafting the
> > Version 2.0 requirements document.
If measurements are not included as valid XML datatypes they will need to be defined as such by other organizations. Each such organization will invent its own mechanism for this and these will not interwork. This negates the concept of XML being a universal data interchange format.
At the 28th October 2000 meeting of the UK Data Harmonization Group that is preparing Core Component definitioins for ebXML the ebXML measure data representation type was identified as having precedence over number, rate, etc. While ebXML may, for the time being, be able to define this type in terms of two component parts, a decimal units value and a string units value, users do not think in these terms and our applications will be required to be able to enter 10kg or 5.25lb/ft^2 as a single, unvalidated, field. We will need to use patterns to split these into two components. As XML patterns do not have the mechanisms provided by other pattern languages to link parts of patterns to named variables this will need to be done in a non-standardized way outside of XML, rather than using a simple standardized mechanism.
NB I liked the idea of parts of patterns, but you need to add a variable="x" attribute to it to allow that part of the pattern to be stored for subsequent reuse. I would like to see a Python-like method of identifying parts of patterns that require subsequent processing.
Martin Bryan
Chair, CEN/ISSS Defining and Maintaining Semantics and Datatype working group